Barium salts of n-aliphatic amides of benzene hydroxy carboxylic acids



United States Patent 4 Claims. (Cl. 260559) This application is a division of application Serial No. 831,051, filed August 3, 1959, now U.S. Patent 3,110,670.

This invention is drawn to a novel composition of matter, to Wit: the barium salts of primary N-alkyl amides of benzene hydroxy carboxylic acids and-lubricants containing these salts.

U.S. Patent 2,337,380 describes a lubricating oil containing calcium N-diamyl salicylamide which has improved properties with respect to oxidation. However, the barium salt of this amide is not soluble in oil to a material extent and it is frequently desirable to add an oxidation inhibitor as the barium salt.

As is well known, mineral oil based liquid lubricants especially motor oilssuifer from the effects of oxidation when used in high temperature applications. The oxidation of the parafiin hydrocarbons included in a mineral oil lubricant yields a number of, organic acids. Naphthenic hydrocarbons probably oxidize and yield oxy productsacids, alcohols, ketones, etc.-in a manner very similar to the paraflins. Aromatic hydrocarbon constitu ents of lubricating oils are readily oxidized, the oxygen first attacking side chains to yield acids and acidic oxy products of the same general types as the parafiins, with subsequent oxidation of the aromatic ring to form complex condensation and polymerization products which tend to be oil-insoluble and which are called sludges.

Many turbine oils and greases contain oil-soluble organic amines and phenol derivatives such as phenyl-anaphthylamine and ,B-naphthol, but these additives are deemed to be essentially low temperature inhibitors, being effective only at temperatures below about 200 or 250 F. and therefore are not suitable for the conditions of temperature and agitation which prevail in engines operating under heavy loads. Mineral oil lubricants designed for high temperature use generally contain sulfur and/or phosphorus compounds to combat oxidative effects but'it is not clear whether these additives actually inhibit the oxidation itself or merely prevent oxidation products from harming the machinery lubricated, since these materials also usually have a detergent function, serving to keep engine parts somewhat free from resin and varnish deposits caused by sludge in the lubricant. Some additives which have been used are aromatic and aliphatic sulfides such as alkyl phenol sulfides, alkyl and aryl phosphites, salts of alkyl phosphoric acids, dithiophosphates, etc., and many of the inhibited motoroils now on the market contain one kind or another of these additives.

In addition, the acidic nature of the oxidation products of a mineral oil lubricant has prescribed the use of basicacting additives for the oil. For this reason salts of the additives mentioned above with Group II metals have received Widespread attention and significant use as inhibitor-detergent additive. Barium is particularly favored as the metal salt-former since it usually can be included in the salt in greater quantities than other Group II metals to give a more basic-acting additive, but barium salts of common inhibitors are frequently not soluble in oil. The oil-solubility appears to be achieved only in a limited 3,282,900 Patented Nov. 1, 1905 ice class of the barium salts of common inhibitors, and these are frequently quite expensive.

The novel barium salts of primary N-alkyl amides of this invention have been found to be relatively low-priced inhibitors of the oxidative effects of high temperatures on lubricants. The effective amount required issmall and the additives are frequently compatible, i.e. soluble, miscible or dispersible, per se in the liquid oil lubricants; that is, they do not require the presence of other additives to exercise a compatibilizing eifect on them and they do not precipitate on standing. Some of the amides may become compatible due to the presence of other additives in the lubricant. These oil-compatible barium primary N-alkyl amides show efiicien-cy as inhibitor-detergents in concentrations as low as about 0.02 weight percent or less in oils of lubricating viscosity. A concentration of 0.01 to 0.1% is preferably used and seldom would the amount be above about 2 to 5%.

Since the sulfur and phosphorus compounds conventionally used in lubricants impart extreme pressure resistant, anti-oxidant and detergent qualities to the lubricant these materials are preferably not eliimnated entirely from lubricants which use the novel barium compounds of this invention, although the quantity of these sulfur and phosphorus additives may be sharply reduced. Oxidation tests indicate as much as a 60% reduction in viscosity rise and lower pentane insolubles in liquid lube oil blends containing reduced levels of barium sulfonate and zinc dithiophosphate when the barium amides of this invention are used.

Barium primary N-alkyl amides may be prepared using the process of copending Nelson application Serial No. 810,531, filed May 4, 1959. The process provides for the direct amidization of hydroxy benzene carboxylic acids with amines using a catalytic amount of a boron oxide, such as boron trioxide or its hydrate, boric acid, in the reaction. To produce the oil-compatible material of this invention, a primary aliphatic amine is used which has a carbon content of about 8 to 32 atoms and generally the hydrocarbon chain of the amine will not contain less than 12 nor more than 20 carbon atoms. The carbon chain can be saturated or unsaturated.

Some amines which can be used to supply the amide portion of the novel compounds of the invention are commerically available fatty amines such as: Armeen HT, a hydrogenated tallow amine comprising approximately 71% octadecyl, 24% hexadecyl, 3% octadecenyl and 2% tetradecylamine; Armeen HTD (distilled Armeen HT); Armeen O, a mixture of oleyl, 6% linoleyl, 5% hexadecyl, 4% tetradecyl and 1% stearylamines; Armeen OD (distilled Armeen O); Armeen 18D, distilled octadecylamine; Armeen C, a mostly C amine derived from coconut; Armeen CD (distilled Armeen C); Alamine H26D, another distilled tallow amine; Primene 81R, a mixture of branched-chain amines containing 12 to 14 carbon atoms; and Primene JMT, a mixture of branched chain primary amines containing 18 to 21 carbon atoms.

Although not all of these amines provide oil-solubility to the barium amide salt, such salts may be used in greases or in liquid lubricants which contain additives such as mahogany sulfonates, dithiophosphates, etc., which exert a solubilizing eifect on these amide salts. Aliphatic primary diamines, such as those commercially available in the Duomeen series which have the requisite carbon content are also suitable materials for amidization by the process of this invention. For example, Duomeen T, a hydrogenated reaction product of tallow amine and acrylonitrile, having a 32 to 50 iodine value and the structure R-NHCH CH CH NH Where R is an alkyl group of 16 to 18 carbon atoms obtained from tallow, may be used.

Sulfurized amines also may be used when it is desired to increase the sulfur content of the finished lubricant, for example, to improve its extreme pressure and other properties. Unsaturated amines, such as Armeen may easily be sulfided by reaction with elemental sulfur or sulfur yielding compounds at an elevated temperature.

The hydroxy benzene carboxylic part of the amide is the residue of an acid having one or more carboxylic acid substituents on the benzene nucleus and one or more hydroxy substituents on the nucleus. Preferably a hydroxy group is ortho to a carboxyl group. Hydroxy toluic acid, halo-, sulfoand amino-hydroxy benzene acids, as well as salicylic acid, to which particular attention is given, may be used so long as the compound is not decarboxylated under the reaction conditions. Di-substituted benzene acids as well as hydroxy benzoic and ipht-halic acids, etc., may be used but long-chain aliphatic substituents may prolong the reaction time unduly, so that loweralkyl substituted benzene hydroxy carboxylic acids make better starting materials.

The acid may be represented structurally by the for-,

mula:

(CO 0H)m where m and n are each one or more, preferably not more than 2, the amide being GONHR (OHM where R is a hydrocarbon radical of 8 to 32 carbon atoms, preferably an alkyl including alkenyl of 12 to 20 carbon atoms, or its equivalent, as described above; that is, NHR is the residue of a primary amine. The barium salt may neutralize one or more of the hydroxyl groups of the amide and may link two aromatic amide molecules.

The amidization reaction is performed readily at temperatures greater than about 160 F. up to the degradation temperature of the reactants or products. An upper temperature limit of about 300 C. or more is usually satisfactory. The lower temperature limit is important from the standpoint of obtaining an oil-soluble product. The amidization is preferably conducted in the presence of a solvent or water-entraining agent such as toluene or xylene in an amount from about to 200% of the weight of the reactants. Apparently, exact equimolecular quantities of salicylic acid and amines are not required. The amide need not be purified before use as an oil-additive. The catalytic amount of boron oxide used in the reaction is usually about 0.5 to 15% or more of the weight of the reactants, preferably about 17% of boron trioxide, boric acid, or a mixture of the two.

The primary N-alkyl hydroxybenzamide maybe converted to its barium salt by direct reaction of the amide with barium hydroxide. The hydroxide may preferably be added as a slurry in part of the base mineral oil which is to be used as the liquid lubricant. The barium may be used in a stoichiometric amount to produce the neutral salt or in an excess amount to give the basic salt. It is also possible to react the hydroxybenzamide with a simple alkali such as sodium or ammonium hydroxide to form the, for example, sodium phenolate, and thereafter react the phenolate with barium chloride to form the barium salt by metathesis.

The oil base stock which is given improved oxidation resistance by the inclusion of a barium primary N-alkyl amide is of lubricating viscosity and can be for instance a solvent extracted or solvent refined mineral oil obtained in accordance with conventional methods of solvent refincomplex esters of long-chain fatty acids with alcohols.

and glycols, esters of dibasic acids such as di-(Z-ethylhexyl) sebaca-tes, adipates and the like, polymerized cracked wax, polygolycol esters, polyglycol ethers, polyglycol ether esters, etc..

As mentioned above, the novel inhibitor of this invention may be used in a lubricant in conjunction with sulfur and phosphorus compounds. One class of compounds in widespread use today are the metal dialkyl dithiophosphates, which can be included in the lubricant in amounts of from about 0.01 weight percent up to about 10 weight percent and which can be obtained from a wide variety of diester dithiophosphoric acids conventionally prepared by reacting a sulfide of phosphorus, such as phosphorus pentasulfide, with an alcohol, phenol or mercaptan. The organic groups in the acid esters may be aryl, alkyl, aralkyl or cycloalkyl groups which contain from about 4 to 20 carbon atoms, preferably up to about 14 carbon:

atoms and may be further substituted in the organic portion. Suitable alcohols which may be used inpreparing the acid esters include primary and secondary alcohols such as 2-methylamyl alcohol, 4-methylpentanol-2, 2-methylpentanol-1, 2-ethylhexanol, di-isopropyl carbinol, cyclohexanol, butanol-l and octadecanol-l, or mixtures such as of high and low molecular weight alcohol or mixtures such as hexanol-heptanol. Other hydroxy-containing materials which can be reacted with phosphorus sulfide include phenols and alkylated phenols such as dioctyl phenol, tIi-isobutylphenol and the like. The metal thio phosphate is conventionally manufactured by oxide or hydroxide neutralization of the acid ester. A number of metals may be used to form the thiophosphate, among.

which are calcium, zinc, nickel, molybdenum and other polyvalent metals.

The alkaline earth metal sulfonates which may be used in lubricant compositions containing the novel primary N-alkyl amides of this invention are those which are.

soluble in the lubricant base oil and obtained, for instance, by neutralizing aromatic sulfonic acids with the hydroxides, chlorides, oxides orother inorganic compounds of the alkaline earth metals. The preferred aromatic sulfonic acids are the oil-soluble mahogany sul-. fonic acids which can be derived from the treatment of a suitable petroleum oil, such as a liquid petroleum distillate boiling in the range of about 600 to 1000 F.', with fuming sulfuric acid or sulfur trioxide, separating the resulting acid sludge from the acid treated oil and recovering the mahogany acidscontained in the acid treated oil. The useful mahogany acids generally have a molecular weight of from about 300 to 500 or more, and

although their exact chemical structures may vary, it

sulfonic acids; such as benzene sulfonic acids and naph thalene sulfonic acids, which include the oil-soluble alkylated aryl sulfonic acids in which the alkyl chain contains from 8 to 18 carbon atoms, for instance, dinonyl naphthalene sulfonic acid, and those prepared by reaction of paraflin wax alkyl chains of 20 or more carbons with aromatic nuclei which are then sulfonated by fuming sulfuric acid, e.g. wax substituted naphthalene. The aromatic oil-soluble sulfonic acids are conveniently employed as a concentrate in the hydrocarbon from whichthey are derived and are usually present in an approximate 10 to 30 weight percent concentration.

The alkaline earth metal sulfonates can be neutral or basic sultonates; by basic sulfonates ismeant those sulfonates in which the alkaline earth metal is present in an amount in excess of that theoretically required to react with the sulfonic acid from which it was made. For instance, when a basic barium sulfonate is employed, there are usually at least about 1.5 equivalents of barium in the sulfonate and in the case of basic calcium sulfonate at least about 1.2 equivalents of calcium. Usually the basic alkaline earth metal sulfonates do not have to have more than equivalents of alkaline earth metal. Also, suitable for inclusion are the oil-soluble carbonated neutral or basic alkaline earth metal sulfonates.

The sulfonates may be included in the lubricant in amounts ranging from about 0.01 weight percent up to about weight percent and are advantageously employed in the oil solution in which they are prepared. If desired, the sulfonates can be recovered by extraction with a low molecular weight alcohol, such as isopropanol or ethanol, followed by distillation for use in the oil-tree form.

Other materials normally. incorporated in lube oils to impart special characteristics can be added to the lubricant compositions of this invention. These include corrosion inhibitors, anti-wear agents, etc. The amount of these additives included in the composition usually ranges from about 0.01 weight percent up to about 10 weight r O and a SUS viscosity at 100 F. of 150. Into an open beaker on a hot plate equipped with a motor driven stirrer and thermometer, 920 g. of the oil described and 79 g. (0.2 mole) of the oleyl N-salicylamide described above were charged. The mixture was heated to 230 F. with stirring. Then 29 g. (0.1 mole) of barium hydroxide pentahydrate were added batchwise over 10 min. The rate of addition was determined by the amount of foaming. The color of the solution changed with the addition of the barium hydroxide from tan to greenish to dark brown. The temperature was raised to 300-320 F. to insure dehydration. The mass was then cooled to 250 F., one weight percent Supercel filter aid was added, and the mass was filtered under vacuum.

The resulting solution contained 9.6% of the barium salt of N-oleyl salicylamide. The salt did not precipitate on standing. The solution contained 1.57 barium and 0.03% boron and had a base number to pH 4 of 19.9.

EXAMPLE II pared as in Example I, using Armeen HTD, Armeen 18D and Alamine H26D. 9.6% oil solutions of these barium salts had the properties reported in Table I.

percent, although the best multi-purpose gear. oils require a combination of extreme pressure additives amounting to about 5 to 20% of the total weight of the lubricant, usually about 813% The following example shows the preparation of an N-alkyl salicylamide and its barium salt.

EXAMPLE I Into a 3-liter, round bottom, 4-necked flask equipped with a voltage regulated heating mantle, thermometer, motor driven stirrer, reflux condenser and water trap were charged the following: 138 g. (1 mole) salicylic acid U.S.P. grade, 275 g. (1 mole) Armeen O and 100 g. commercial xylene. Heat was applied to the flask and agitation started. After eleven minutes the temperature was 224 C. and the xylene started to reflux. During the next 7 /2 hours 5 cc. water and 30 cc. xylene were removed through the trap. The xylene was removed to increase the reflux temperature. The mass was then allowed to cool from 260 C. to 140 C., 4 g. boric acid were added, and heat was again applied. The mass was heated for an additional 16%. hours during which time 7 g. of boric acid in increments of 4 and 3 g. were added. The mass was then blown with nitrogen for 15 minutes up to 285 C. The yield was 85.5% of theory. This product had a saponification number of 5.7, an acid number of 4.4, a hydroxyl value of 191 and contained 0.61% boron. It was oil-soluble.

An oil-soluble barium N-alkyl salicylamide was prepared from this amide as follows, using a Mid-Continent neutral solvent refined oil having a viscosity index of 95 All of these salts were soluble, but precipitated from solution in the oil at this relatively high content.

Table II, below, shows the results of oxidation tests performed upon lubricant blends containing varying proportions of a barium N-tallow salicylamide similar to that of Sample III. The base liquid mineral lubricating oil was a blend containing 51% by volume of a solvent refined neutral distillate having a viscosity of 200 SUS at F. and a viscosity index of 95, and 49% by volume of a solvent refined Mid-Continent residual oil having a viscosity at 100 F. of 1870 SUS and a viscosity index of 90. The blends contained varying amounts of a basic barium mahogany sulfonate made by sulfonation with sulfur trioxi-de of a dewaxed Mid-Continent lubricating oil fraction having a viscosity of 250 SUS at 100 F. and a 70 viscosity index, and then neutralized with barium hydroxide and added to the mineral oil base as a 15 to 20% concentrate in its starting oil. The blends also contained varying amounts of zinc di(2-methyl-pentanol-4), dithiophosphate diester added as a 50% concentrate in mineral oil, as well as 0.005% of a silicone anti-foaming agent. The results obtained using a lubricant without the novel additive of the invention, as well as a lubricant containing a higher proportion of the sulfonate are also reported. In each case, the amide was added as the 9.6% oil solution described above.

The test is one of oxidation characteristics of railway diesel lubricants (Railroad Oxidation Test) wherein five liters of oxygen per hour are bubbled through a 300 ml. sample of the lubricant in the presence of a steel-backed copper-lead catalyst.

Table 11 Sample 022 201 122 121 180 181 Additive (percent):

Ba mahogany sulfonate concentrate 7. 8 5. 9 5. 9 5. 9 5. 9 5. 9 Zinc dithiophosphate concentrate- 1. 8 1. 8 1.8 1. 8 1. 8 1. 8 Ba N-tallow salicylamide solution 1. 0. 0. 25 0. 1 KV/ 0 F 112. 7 114. 6 101. 9 107. 9 110. 7 112. 6 210 F 11. 63 11. 75 10. 92 11. 24 11. 45 11. 58 Barium, percent 0. 51 0. 39 0. 45 0. 40 0. 4O 0. 36 Sulfur, percent 0. 36 0. 35 0.36 0.32 0. 34 0. 33 RR Oxidation Test:

SV 00 F 963 1, 034 610 572 651 688 KV/100 F 207. 8 223. 1 131. 6 123. 4 140. 4 148 Viscosity Rise, percent 82 94. 5 29.0 14. 3 21. 2 31. 8 Catalyst Wt. Change, mg 2. 5 2. 9 13. 2 5. 5 2. 2 1. 7 Acid Number 6. 0 6. 1 6. 2 4. 6 5. 4 5. 3 Pentane 111501., percent- 0.9 2. 7 0. 03 0.01 0. 04 0. 06 Initial pH 1. 4 2. 2 1. 7 1. 7 1. 9 1. 8

I claim: References Cited by the Examiner 1. Thfi barium Salt Of a amide having the structural formula:

2,337,380 12/1953 Finley et a1 260559 X (000m 2,655,479 10/ 1953 Munday et a1. 252-79 2,764,614 9/1956 Meyer 260-559 0 ONHR 2,923,735 2/ 1960 Erlenmeyer 2605 19 2,959,550 11/1960 Young et a1 252.40.7

OTHER REFERENCES Hirwe et a1.: Proc. Indian Acad. Sci., vol. 5A, pages 21 Where R is a primary N-alkenyl radical of about 12 to 20 3o 3 carbon atoms and m and are 1 to WALTER A. MONDANCE, Primary Examiner.

2. The composition of claim 1 where m and n are 1. 3. The composition of claim 2 Where R is olcyl. NICHOLAS RIZZO JOHN RANDoELpHi xammers.

4. The composition of claim 3 where the amide is salicylamide. R. PRICE, N. TROUSOF, Assistant Examiners. 

1. THE BARIUM SALT OF A PRIMARY N-ALIPHATIC AMIDE HAVING THE STRUCTURAL FORMULA: (HOOC)(M-1)-,(R-NH-CO-),(HO)N-BENZENE WHERE R IS A PRIMARY N-ALKENYL RADICAL OF ABOUT 12 TO 20 CARBON ATOMS AND M AND N ARE 1 TO
 2. 